There are many fluid valves available for use with fire extinguishing systems which provide quick response times between a closed and secure position to an open position. U.S. Pat. Nos.: 4,579,315, 3,196,953, and 3,187,499 show examples of such valves. These valves have several limitations which restrict their use to a particular application. One particular valve application with very stringent environmental requirements is in connection with an on-board fire extinguishing system for use within a military tank vehicle. As further discussed below, the prior valves are unable to withstand the relatively harsh environment commonly found within a tank vehicle and would likely malfunction and/or trigger falsely.
All of the above-mentioned patents disclose valve assemblies which include a tripping means for activating the valve and the connected extinguishing system. The tripping means generally consists of a pivotal member or arm that is movable against the action of a spring or the pressure of the system extinguishant. The arm is usually connected directly or indirectly to a seal which keeps the extinguishant within the system until needed (i.e., valve in a closed position). The valve is retained in the closed position using a biasing spring or a retaining clip as in the case of U.S. Pat. No. 3,924,687.
A problem with the retaining means of the prior valves is that they cause the entire valve to become susceptible to false triggering due to relatively harsh environmental conditions such as excessive vibration or sudden movement. Such vibration or sudden movement is quite common in a military tank environment. If any of the prior valves were installed in a fire extinguishing system of a military tank, the system would invariably trigger accidentally owing to tank vibration caused by its engine or its travel over rough terrain, for example, or any sudden movement such as a projectile impact (incoming) or the tank running into a stationary object such as a tree or rock or the sudden weight- shifting movement caused by the firing of a projectile (out-going). Since the extinguishant currently used in military vehicles is generally in the form of a pressurized gas such as Halon 1301 and stored in a finite amount on the vehicle, any accidental triggering of the system could cause harm to both the vehicle and its surprised operators in time of battle. Accidental misfiring of the system would leave a vehicle, remote in the field, without system protection against any future (actual) fires.
The retaining clip disclosed in U.S. Pat. No. 3,924,687, furthermore is meant to melt away when the temperature of the immediate environment reaches a prescribed temperature. It is common, in the above military tank vehicle application, to have several separate compartments, each capable of reaching different maximum temperatures during operation. Examples of such compartments might include an engine compartment, a living compartment, an ammunition compartment, and perhaps a fuel compartment. In a military tank having a extinguishing system with release valves like that disclosed by U.S. Pat. No. 3,924,687, an engine compartment sensor could mistake a relatively harmless overheating engine as a compartment fire and therefore trigger the system, wasting valuable extinguishant. The same system could also misfire in a situation where the heat sensitive clip of U.S. Pat. No. 3,924,687 softens and extreme vibration, as discussed above, causes the weakened clip to break, thereby opening the valve.
Another problem associated with the prior valves available for fire extinguishing systems operating in such harsh environments is that commonly the outlet nozzles and triggering mechanisms are inaccessible and therefore difficult to reset after a system triggering. It is necessary to close all the nozzles prior to recharging the system with Halon extinguishant, for example. The nozzles are located in the different compartments of a military vehicle and are inaccessible will extend the time required to refill and reset the triggered system.
Another problem associated with fire extinguishing valves using a gaseous system extinguishant such as Halon 1301 is that the seals within the valves are unable to maintain system pressure. The seals can leak over a period of time, creating a useless or less effective extinguishing system when activated. Another problem with the prior fire extinguishing systems is that there is no provision to activate any particular outlet nozzle from a location remote to the nozzle itself through a quick and easy means such as an electrical switch. Also, the prior nozzles fail to provide a back-up trigger for manually activating any particular nozzle at the location of the nozzle.